Abstract

This paper describes a purely optical technique for measuring and spatially mapping out stress and rigidity in thin membranes. Its application to a membrane of aluminum nitride that has significant spatial nonuniformities in its elastic properties demonstrates the method. The attractive features of this technique—fast, noncontacting measurement, good spatial resolution, ability to quantify in-plane anisotropy—make it potentially useful for characterizing elements of microelectromechanical structures, masks for advanced lithographysystems, acoustic filters, and other devices in which the mechanical properties of membranes are important.